Section 9.6

A group of stars held together by gravity Open star clusters – collections of 6 to 1000s of younger stars Globular clusters – ball shaped collection of 1000s to s of very old stars

Collections of millions/billions of stars, planets, gas and dust measuring up to ly across. Come in different shapes/sizes – Elliptical – spherical to flat oval shape – Spiral – spinning pinwheels – Lenticular – central bulge surrounded by flattened disc – Irregular – no definite shape

2 spiral arms, central bulge of old stars, disc of newer stars around the bulge Our solar system is located on the inner edge of one of the spiral arms ( ly from the inner core). There is a supermassive black hole at the center

They are distant, young galaxies that emit large amounts of energy produced by a supermassive black hole at its centre. The central region is more luminous than normal – they look like stars though a telescope

Pg. 387 Classifying Galaxies – Complete #1, A-E (yes…E will be homework) Pg. 391 #1, 6, 8